I found that I needed to adjust the pocket holes for the backrest slats. If there is a next time I would cut the pieces to 32 not 31 inches and then make the marks. At 31 inches the piece didn't reach to the top of the top slat, which is what it showed in the pattern. If you are not spacing the back slats apart you won't need to adjust anything.

The bottom pocket holes are the original ones. You can see how close to the edge of the 2 x 4 they were. By the time you reached the top slat (after spacing them out) there was almost no room to attach it.